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Old Jul 24, 2008, 03:40 PM
Registered User
Joined Jul 2008
14 Posts
Question
Giant Super Super Sportster Right Thrust?

I just finished the Giant Sportster and installed the 3.2 Fuji gas engine according to spec/instructions in their assembly manual.
After assembly, I noticed the engine has "Right Thrust" about 5 degrees (didn't measure it yet).
Nowhere in the manual does it refer to right thrust from center engine line.

I payed particular attention to the photos in the manual (as there is no mention of right thrust) and all is according to the visuals in the manual.
Is it possible ( I know many gassers have right thrust) that this is incorrect for this plane?????

thanks in advance
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Old Jul 24, 2008, 04:53 PM
Mach 1
pathfinder's Avatar
walterboro s.c.u.s.a
Joined Jun 2004
755 Posts
I have a giant super sporster with an OS120 4cycle on and it.I dont remember putting any right thrust in it.I know mine is a 4cycle and yours is a gasser.I would interested myself, to see if there is a difference in the way the two should be mounted..

jimmy.p.
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Old Jul 25, 2008, 01:03 AM
NM2K
Ringgold, GA, USA
Joined Jan 2006
1,045 Posts
Quote:
Originally Posted by djmarchand
I just finished the Giant Sportster and installed the 3.2 Fuji gas engine according to spec/instructions in their assembly manual.
After assembly, I noticed the engine has "Right Thrust" about 5 degrees (didn't measure it yet).
Nowhere in the manual does it refer to right thrust from center engine line.

I payed particular attention to the photos in the manual (as there is no mention of right thrust) and all is according to the visuals in the manual.
Is it possible ( I know many gassers have right thrust) that this is incorrect for this plane?????

thanks in advance

-------------


Two or three degrees of right thrust will help you tremendously during the takeoff run. Once in the air, you won't notice it being there, unless you do not have it. However, five degrees is too much. Two degrees would be perfect.

Engines with large, slow turning props introduce quite a bit of left turn due to the model trying to roll to the left as the prop turns to the right (cockpit view). This left roll pushes the left wheel down harder than the right wheel. The added drag on the left wheel turns the model to the left while still running along the ground.

Right thrust also helps keep the model flying straight ahead when performing steep climbs, such as that induced while performing a loop. Without a tad of right thrust, the model will tend to spiral off to the left. A really advanced pilot would not use any right or downthrust at all, but would instead compensate with the flight controls by anticipating the model's needs and correcting the model early while the inputs needed would be small.

However, if you are a low time pilot (I have no way of knowing), it would be best to use some right thrust during your acclimation phase. Larger models tend to exagerate some of the torque induced problems, but not to the point where they cannot be learned and dealt with properly. Relax and enjoy. Just don't fly that model with more than three degrees of right thrust.

Ed Cregger
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Old Jul 25, 2008, 07:42 AM
Zor
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Ontario,Canada
Joined Feb 2007
9,742 Posts
Hello djmarchand,
Some comments in red.

Quote:
Originally Posted by djmarchand
I just finished the Giant Sportster and installed the 3.2 Fuji gas engine according to spec/instructions in their assembly manual.
After assembly, I noticed the engine has "Right Thrust" about 5 degrees (didn't measure it yet).

- If I understand you properly, just below you say "Nowhere in the manual etc. . . and just above you say "After assembly, I noticed Etc. . .
- Can you see from the manual how the 5 degrees of side thrust were established (took place).?
Nowhere in the manual does it refer to right thrust from center engine line.

I payed particular attention to the photos in the manual (as there is no mention of right thrust) and all is according to the visuals in the manual.
- It must not be easy from photos to see if there is or there is not a 5 degrees side thrust or judge how many degrees there is. Even if a photo was straight down, judging 2 or 3 or 5 degrees is not easy and you also say "you did not measure the angle".
Is it possible ( I know many gassers have right thrust) that this is incorrect for this plane?????
- Not only gassers have right thrust, many engines using glow fuel or electric motors also are specified with right thrust or some side thrust in some models.
thanks in advance
Looking forward to your measurements results.

Red comments from Zor
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Old Jul 25, 2008, 03:44 PM
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Joined Jul 2008
14 Posts
thanks Artisan and Zor

I did measure the thrust angle and there is 3 degrees that is designed into the firewall and not the engine mount.
Your explanations are very helpful and am looking forward to first flights this weekend...!
thanks again.
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Old Jul 26, 2008, 08:41 AM
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moreno valley california
Joined Jun 2008
303 Posts
right thrust is used to compensate the force of the propeller slipstream against the rudder. at low speeds and high rpms (take off) that force will cause a left turning tendency which dissipates as the airplane accelerates. i do remember reading an article years back about a pattern plane that had 5 degrees, but 2 to 3 is the "norm" and these day it is common to have it prebuilt into the fuselage. what you would notice if you took it out is that you would need more rudder during takeoff and the plane would wander left whenever there was low speed and high engine rpm. good luck on that maiden....and so called advanced pilots spend time finding the proper offset to ensure that the airplane will track straight during vertical maneuvers.
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